More than 50 people have been killed and 15 are missing following floods, landslides and mud flows that hit parts of central and southern China following days of torrential rains, the Ministry of Civil Affairs said Saturday.

Nearly 17.2 million residents in nine provinces were affected by flood-related disasters and 597,000 people were relocated from July 1 to 12 a.m. of July 10, the ministry said in its latest disaster relief update.

About 946,500 hectares of farmland were damaged, including 133,900 hectares that were completely destroyed. Further, more than 42,000 houses collapsed and another 121,000 were damaged, the ministry said, estimating that direct economic losses could reach 8.9 billion yuan (1.3 billion U.S. dollars).

The ministry sent 6,000 tents to the hardest-hit Hubei Province in central China and Chongqing Municipality in southwest China on Saturday.

In June, torrential rains had resulted in 260 deaths and left 211 missing in 11 southern provinces.

The latest round of storms began to pound large swaths of central and southern China on July 8.

In Hubei, the local weather forecast bureau said storms or thunder storms could hit the province again from July 11 to 13. It warned that rainfall would exceed 300 millimeters in some worst-hit areas, which was likely to trigger another round of heavy floods.

The Three Gorges Dam, sitting in the middle reach of the Yangtze River in Hubei, on Saturday released water for the first time this year.

Engineers opened three sluice gates to discharge some 32,000 cubic meters of water per second and another sluice gate to release floating objects.

The flood from the upper stream reaching the dam was measured at 36,000 cubic meters of water per second and could increase to 39,000 cubic meters per second by Sunday, dam officials said.

Authorities said water levels in many branches of the 6,397-meter-long Yangtze River that runs from west to east, had gone above the warning lines. At Wulong monitoring station in Chongqing the water level was three meters above the warning line.

In southwest China's Guizhou Province, several counties and villages were submerged in more than one meter deep water. About 7,500 residents were evacuated from the flooded zones.

Also, four miners were killed in a gas explosion after heavy rain cut off electricity and stopped ventilation equipment at a coal mine in Xishui County of Guizhou's Zunyi City early Saturday morning. Seven of the 25 miners who were working underground managed to escape when the explosion occurred. Rescuers later saved 14 other miners.